1. Field of the Invention
The present invention relates to electrical machines.
2. Description of the Related Art
Lundell or "claw pole" alternators are well-known, for example as electrical generators for motor vehicles. Such machines have very attractive attributes such as low cost and a mature design. However, with the ever-increasing electrical accessory content on motor vehicles, the need for greater electrical generating capacity is needed.
Certainly, one option is to use larger and larger Lundell alternators. However, the generally reducing size of vehicles makes packaging larger and larger alternators difficult. Thus, an alternator with a higher power density (that is, more power output per unit volume of the machine) than a conventional Lundell alternator can prove advantageous.
However, as was mentioned above, Lundell alternators themselves have considerable advantages. Thus, an electrical machine design which preserves the advantages of a conventional Lundell machine while increasing its power density will provide advantages over alternative designs. Increasing the power density of the Lundell machine without abandoning the basic Lundell design can certainly help preserve the cost advantages of a Lundell machine. Also, using a modification of the basic Lundell design can allow the wealth of design and manufacturing expertise which has been developed in connection with Lundell machines to continue to be used.
Therefore, an electrical machine design which can provide higher power density within the general parameters of Lundell machine design can provide advantages over the prior art.